Fitting swissporPIR Alu insulation within a fixed roof height

On the sketch, draw a dimension from the top of the deck to the finished level. The swissporPIR Alu board contributes a rigid PIR core with an aluminium, paper and polyethylene laminate on both sides. Support and waterproofing occupy separate positions in the section. The laminate cannot serve as the structural steel facing of a sandwich panel.

The manufacturer gives a thermal conductivity of 0.022 W/(m·K). The 100, 120 and 160 mm boards have declared thermal resistances of 4.50, 5.45 and 7.25 m²K/W respectively. Use the listed resistance for the selected board in your calculation.

Moving from 100 to 120 mm adds 0.95 m²K/W of declared resistance and raises the top of the boards by 20 mm on the same deck. Enter both changes on the section. Determine the U-value from a calculation including the other layers and applicable corrections.

Transfer the measured width between the parapet and the first row of rooflights to the cutting plan. Compare layouts using 1200 × 600 mm and 2400 × 1200 mm boards. Mark where each layout retains a factory edge and where cutting leaves a square edge.

Specify edge profile, thickness and format together in the order. The 20–300 mm thickness range covers the product offering as a whole. Confirm delivery for the combination selected, particularly if the perimeter needs a different format from the main roof area.

At a rooflight, take measurements on both the high and low sides. Mark the finished roof level against the kerb at each point. Even with identical insulation thickness, the fall can leave different heights for turning up the waterproofing.

Before covering the first bay, inspect the junction between the horizontal board and the kerb insulation. A photograph with a scale should show the corner and the height allowed for flashing. It provides a reference for later rooflights once the first detail is concealed.

The specified CS(10/Y) value for swissporPIR Alu is at least 150 kPa. It describes compression under test conditions. Beneath a unit that will remain in place for years, also assess creep, the footprint of the support and the stiffness of the load-spreading component.

Mark how the support passes through the layers and how water drains around it. The board has reaction-to-fire class E. Where the roof needs a fire classification for the complete assembly, check that it covers the actual combination of layers.

For the thicker option, price any raised flashings and alterations to rooflight kerbs. For the thinner option, establish whether its calculated U-value meets the brief. Compare costs over the same roof area once each option meets the requirements.

Attach the cutting layout and the number of whole boards allocated for cutting. The parapet strip can then be priced using actual material consumption, crediting reusable pieces and avoiding counting the same offcut as waste in two areas.

Suppose 150 mm is available for the build-up after allowing for the required threshold upstand, and other layers take up 30 mm. That leaves 120 mm for insulation. The 160 mm board exceeds the available depth by 40 mm. If 120 mm cannot deliver the required U-value, revisit the threshold detail or the roof build-up.